I found this v. interesting article on a forum. I’ve copy and pasted a snippet of it.

Steve Dale writes :-

“I know a parrot in New York called N’kisi (a Congo African Gray parrot) who knows 971 words. He isn’t counted as having a new word until he’s used it at least five times in a proper context. In other words, if he just repeats a word, that doesn’t count. Before I met N’kisi, his owner, Aimee, was showing him pictures of me and chimps. When I walked into the room, he asked, ‘Got a chimp?’ Aimee broke a necklace, and he said, ‘What a pity. You broke your new, nice necklace.’ He uses grammar and initiates conversation (all skills once reserved for people). This bird even has a Web site [sheldrake.org/nkisi]. I don’t think he’s an exceptionally brilliant parrot; I do think we’re only starting to understand how smart they are.”

To read the full article, go here – http://www.websitetoolbox.com/tool/post/nicko62/vpost?id=2575336